1. Field of Invention
Embodiments of the invention relate generally to a system and method for chemical mechanical polishing.
2. Background of Invention
In semiconductor wafer processing, the use of chemical mechanical planarization, or CMP, has gained favor due to the enhanced ability to increase device density on a semiconductor workpiece, or substrate, such as a wafer. As the demand for planarization of layers formed on wafers in semiconductor fabrication increases, the requirement for greater system (i.e., process tool) throughput with less wafer damage and enhanced wafer planarization has also increased.
An exemplary CMP system that addresses these issues is described in U.S. Pat. No. 5,804,507, issued Apr. 15, 1998 by Tolles et al., which is incorporated herein by reference in its entirety. Tolles et al. discloses a CMP system having a planarization system that is supplied wafers from cassettes located in an adjacent liquid filled bath. A transfer mechanism, or robot, facilitates the transfer of the wafers from the bath to a transfer station. The transfer station generally contains a load cup that positions wafers into one of four processing heads mounted to a carousel. The carousel moves each processing head sequentially over the load cup to receive a wafer. As the processing heads are loaded, the carousel moves the processing heads and wafers through the planarization stations for polishing. The wafers are planarized by moving the wafers relative to a polishing material in the presence of polishing fluid. The polishing fluid typically contains chemicals that aid in the removal of material from the wafer. The mechanical aspect of the polishing process is generally provided by abrasives disposed either in the polishing fluid (i.e., slurry) or disposed on the polishing material. After completion of the planarization process, the wafer is returned back through the transfer station to the proper cassette located in the bath.
As increased numbers of integrated circuit fabrication schedules include one or more chemical mechanical planarization steps, demand for chemical mechanical polishing tools having greater wafer throughput and decreased cost of ownership has become paramount. Thus, tools having small footprints and high production capacity while minimizing defects rates are in great need.
Therefore, there is a need for an improved chemical mechanical polishing system.
One aspect of the invention generally provides a system for processing a substrate. In one embodiment, a system for processing a substrate comprising a polisher, a first motion device, a second motion device and a load cup is described. The polisher has one or more polishing heads and one or more platens. The polishing heads are adapted to retain the substrate against the platens during processing and provide motion therebetween. The first motion device is disposed proximate the polisher""s first side and moves along the first side between at least a first position and a second position. The second motion device is coupled to the first motion device and the load cup. The second motion device moves the load cup between at least a first position that is adjacent the first side and a second position that is inward of the first side.
In another embodiment, a system of processing comprises a polisher, a first motion device, a first load cup, a second motion device, a second load cup. The polisher has one or more polishing heads and one or more platens. The polishing heads are adapted to retain the substrate against the platens during processing and provide motion therebetween. The first motion device is disposed adjacent the polisher""s first side and is movable along the first side of the polisher. The first load cup is coupled to the first motion device. The second motion device is disposed adjacent the polisher""s second side. The second side of the polisher is orientated opposite the first side. The second motion device has the second load cup coupled thereto and is movable along the second side of the polisher.
In another aspect of the invention, method for chemical mechanical polishing is provided. In one embodiment, the method includes the steps of transferring the substrate into a first load cup located in a first position, moving the first load cup proximate a first side of the polisher to a second position, moving the first load cup to a third position inward of the second position, and transferring the substrate from the first load cup in the third position to the polishing head. In another embodiment, the method includes transferring a first substrate in a first load cup from a first side of the polisher towards a first polishing station, transferring the first substrate to a first polishing head that is supported by a first carousel, polishing the first substrate on the first polishing station, transferring the first substrate while retained in the first polishing head to a second polishing station, polishing the first substrate on the second polishing station, transferring the first substrate to a second load cup, transferring the first substrate in the second load cup away from the second polishing station towards a second side of the polisher that is opposite the first side.